Recorder drum for facsimile apparatus



April 28,1953 M. ALDEN 2,636,801

RECORDER DRUM FOR FACSIMILE APPARATUS Filed Jan. 3. 1950 Patented Apr. 28, 1953 UNITED STATES PATENT OFFICE RECORDER DRUM FOR FACSIMILE APPARATUS Milton Alden, Wellesley', Mass. I Application January 3, 1950, Serial No. 136,513

1 This invention relates to facsimile recorders of the type described in my copending patent application No. 136,511, filed January 3, 1950, and more particularly to" an improved drum for carrying the helical conductor. In a conventional recording drum the conducting wire is wound helically upon the outer periphery thereof so that it projects above the drum'surface as illustrated in my above mentioned application, and is subject to considerable wear and abrasion by the passage of the record ing paper thereover, the top sector of the wire soon becoming worn away so that the mechanical resistance of the wire 'to the movement of the paper increases. velops edges which scuff the paper and in some instances become sharp enough to tear the paper. Accordingly objects of this invention are to provide a facsimile recording drum which has disposed along the outer periphery a helically arranged conductor, which isarranged so that the conductor does not developsharpedges with use, which does not tear the recording paper, which is strong and durable. in construction,

which can be economically manufactured andwhich advances the art generally.

In a principal aspect the invention contemplates a drum which has formed thereupon a helical track in the form of a ridge, track, or

projection from the drum and having a fiat top.

The recorder drum and track are of conductive material and a coating of nonconducting plastic or other insulating material is applied to the entire surface of the drum except for the top of the track. Adjacent the track the coating is of the same thickness as the track having shoulders which merge with portions of the coating covering the remainder of the drum. The respective ends of the helical track, which terminate just short of a common geometric element of the drum cylinder, are connected by a raised longitudinal rib of the nonconductive coating which extends along the drum between the opposite ends of the helical track and is elevated to substantially the same height as the track so that the recorder bar is supported as it transfers from one end of the drum track to the other.

Further objects and aspects relate to various features of construction and will be apparent from a consideration of the following description in an accompanying drawing wherein Fig. 1 is an elevation view in partial section of one embodimentof a recorder drum according to the invention;

The resulting sector de-.

5 Claims. (01. 346-74.)

2 Fig. 2 is a fragmentary section on line-2 2 of Fig. 1;

Fig. 3

is a cross section view on line 3-3 of Fig. 1;

Fig. 4 is a section view similar to Fig. ing a second embodiment; and

Fig. 5 is a view similar to Fig. 3 of the second embodiment.

Referring now to Fig. 1 the recorder drum assembly 9| comprises a cylinder 33! which may be cast, machined or extruded of a conducting material, preferably an easily worked metal. The respective ends of the cylinder 331 are closed by the separate end pieces or heads 333. The assembly is supported upon a shaft 335 concentrically attached to the heads 333 so that its respective ends project therefrom to form journals which are inserted in conventional bearings (not shown) secured in the housing or cover of the recorder. The conductor or track 332 is helically arranged upon the outer periphery of the 2 showcylin'der 33! making essentially a single turn along the axial length thereof, the ends 334 terminating just short of a common geometric element of the cylinder drum.

The entire outer surface of the drum is coated with a plastic or other nonconducting material 328 which adjacent to the track 332 on either side thereof has shoulders built up to substantially the same thickness as the track so that the paper being drawn across the drum does not engage the sharp edges at the opposite sides of the track. The remainder of the coating ma terial 333 is thinner but merges smoothly into the built up shoulder adjacent the track portions.

The nonconducting material 338 is also built up as at 336 (Fig. 3) to substantially the same height above the drum surface as that of the track 332, the resulting rib connecting the opposite ends 334 of the helical track so that the recorder bar can make the transition from one end to the other of the raised track without jumping or chattering.

The helical conductor 332 shown in Figs. 1 through 3 can be attached by any of the well known techniques, for example, riveting or hard soldering. As is shown in the embodiment in Figs. 4. and 5 it is also possible to make the track 332a as an integral part of the drum, for example by casting or pressing the track portion outwardly from the body of the drum. The transition rib 336a may be formed in an analogous manner and covered with a layer of nonconducting material of substantially the 3 same thickness as that coating the remainder-of the drum.

The above described drums can beused with facsimile recorders having recording bars of the type which are well known to those skilled in the art and shown in my above mentioned application. As the helical track 332 (or 332a) is worn away by the bar, the adjacent shoulders of the comparatively soft coating. 338 adjacent the track are worn away at approximately the same rate so that the edges of the track are never exposed to tear or scuff the recording.

paper.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

l. A drum for recording apparatus of the type described comprising a conductive cylinder having thereon a raised helical conductive track, the

top surface of which is flat, and a nonconductive coating having a thickness less than the height of the track adhering to the cylinder and completely covering the same except for the top of the track, the portions of said coating adjacent the track forming shoulders on either side thereof whose tops are flush with the top of the track.

2. A drum for recording apparatus of the type described comprising a conductive cylinder having thereon a raised helical conductivetraclr, the top surface of which. is fiat, and a thin nonconductive coating having a thickness less than the height of the track adhering to the cylinder and completely covering the same except for the top of the track, the portions of said coating adjacent the track forming shoulders on either side thereof whose tops are flush. with the top or the track and whose sides merge smoothly with the re- -mainder of the. coating.

3 A drum for recording apparatus of the. type c'uescribed comprising a cylinder'having therein a raised helical conductive track which makes one traverse of the cylinder, the opposite ends of the track terminating just short of a common element of the surface so that there is a gap between said ends, and a nonconductive rib extending longitudinally of the surface of the cylinder between the ends of the track, said nonconductive rib being of substantially the same height as that of the conductive track.

4 A recorder drum for facsimile receiving apparatus of the type described comprising a conductive cylinder having embossed on its surface an f outwardly projecting helical track which makes one traverse of the cylinder, the opposite ends of. the. track term-mating short of a common element of the surface of the cylinder so that there is a gap between the ends, said cylinder also having embossed on its surface an outwardly projecting straight rib extending longitudinally of thecylinder between the ends of the helical track, and'a coating of nonconductive material adhering' to the cylinder and completely covering the same exceptior the top of the track, the thicknesjsof said coating adjacent the track being such. as to form shoulders on either side of the track the tops of which areflush with the top of the: track, the thickness of. the coating covering the rib being of. a depth. sufficient to make the combined. height or the rib and the coating substantially equal to the height of the helical track.

fiuln. a facsimile receiving. apparatus of the typeidescribed including a. recorder drum and a recorder bar arranged to engage the drum: and to ridethereon, a track of conducting material on the drum upon which the bar rides, said track being formed by a. helical ridge projecting from the surface of; the drum. and a nonconductive coating covering the entire surface of. the drum except for the top surface of the track, the thickness-" of said coating: adjacent: the track being such as to form. shoulders on. either side of. the track. the tops of which are flush with the top of the track.

MILTON ALDEN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,909,142 Zworkykin et al. May' 16, 1933 2,227,109- Shankweiler Dec. 31., 1940 2,391,765 Artzt Dec. 25, 1945 2,415,229 Young i Feb. 4, 1947 2,486,890 Tribble Sept. 6, 1949 

